Increased concern for terrorist activities has greatly intensified interests in the use of creatures such as explosive sniffing dogs (canines), honeybees and rats, and also sensitive analytical instruments, for the detection of explosives. As a consequence, a need for improved, easy to handle training and calibration aids has emerged. To meet this need, several efforts have been made to develop scent simulants enhancing the process of explosives detection. For example, U.S. Pat. Nos. 5,648,636, 5,413,812 and 5,359,936, to Simpson et al., relate to explosive simulators which are a combination of an explosive material with an inert material, either in a matrix or as a coating, where the explosive has a high surface ratio but small volume ratio. The simulator has particular use in the training of explosives detecting dogs, calibrating analytical instruments which are sensitive to either vapor or elemental composition, or other applications where the hazards associated with explosives is undesirable but where chemical and/or elemental equivalence is required. The explosive simulants may be fabricated by using different techniques. A first method involves the use of standard slurry coatings to produce a material with a very high binder to explosive ratio without masking the explosive vapor, and a second method involves coating inert substrates with thin layers of explosive.
Explosive simulants have also been fabricated for a detection method based on analytical principles. For example, U.S. Pat. No. 5,958,299 issued to Kury et al. relates to methods for fabricating non-energetic explosive simulants, specifically for equipment designed to remotely detect explosives. The simulants are non-explosive, non-hazardous materials that can be safely handled without any significant precaution. The simulants imitate real explosives in terms of mass density, effective atomic number, x-ray transmission properties, and physical form. These simulants are different from those needed for training creatures, as they are fabricated for a detection method based on analytical principles different from those pertaining to creature, particularly canine, detection, or for the calibration of instruments that rely on the principles of headspace vapor sampling to detect detonable materials.
There are several limitations to the types of scent simulants that can be produced from the direct use of real explosives. These limitations stem from the use of a methodology based on principles other than those pertaining to the underpinnings of scent analysis, scent detection, and of pseudoscent formulation. Explosive scent simulants are presently produced by dispersing optimized amounts of the explosive to be simulated within a dispersant, in an attempt to maximize the scent generated while using as little of the explosive as possible. The method leaves unaddressed, issues involving the particular scents generated by explosives, the scents generated by dispersed explosives, scent formulation and control and the relationship of all these to the olfactory capacity, or limitations, of explosive detection creatures.
Accordingly, there is continuing interest in the development of explosive-scent simulants, particularly of scent simulants that do not contain any of the energetic materials, or the explosive capacity, of the explosives they are designed to simulate. This is because, as an additional benefit, it would be possible to handle, transport, and store such energetically-inert pseudoscents in ways that would have been impossible as explosives, and which will present logistical relief for explosive detection programs.